All of the following are true about amiadarone induced thyroid dysfunction except?
Correct Answer: Hypothyroidism is more common in men
Description: Answer is B (Hypothyroidism is more common in men): `Amiadarone associated hypothyroidism is more common in women and individual with positive TPO antibodies' Amiadarone is a class III antiarrythmic agent structurally related to thyroid hormone and containing very high amount of iodine. Mechanism of actionQ: Amiadorone inhibits deiodinase activity. Initiation of Amiadarone treatment - Inhibitory effect of iodine on T4 release - Wolff Choikoff effect: Excess iodine transiently inhibit thyroid iodide organification Transient decrease in T4 levels (Hypothyroidism) - Escape from Wolff Choikoff effect (most individuals escape from iodide dependent supression of thyroid) - Inhibition of deiodination (deiodination is required for conversion of T4 to T3.) Enhanced T4 levels Decreased T3 levels / increased rT3 Elevated TSH levels (TSH levels normalize or are slightly suppressed after about 1-3 months) Amiadarone associated hypothyroidism: Involves an inability of thyroid to escape from high iodine load. Consequently amiadarone associated hypothyroidism is more common in women and in individuals with positive TPOQ. Amiadarone associated hypehyroidism: Two types of Amiadarone induces thyrotoxicosis (AIT) are seen - AIT - Type I AIT - Type II Associated with an underlying thyroid abnormality - preclinical gravis - multinodular goitre Associated with individuals with no intrinsic thyroid abnormality Thyroid hormone synthesis becomes excessive as a result of increased iodine exposure - Jod basedow phenomenon Thyrotoxicosis results from drug induced lysosomal activation leading to destruction thyroiditis. This can resolve spontaneously or can occasionally lead to hypothyroidism Increased vascularity is seen on color-flow dopier scan Decreased vascularity is seen on color flow dopler scan IL6 levels are marginally raised. IL6 levels are markedly raised.
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